a,b,c三个数在数轴上的位置如图,且a的绝对值=c的绝对值,化简|a|-|b+a|+|b-c|+|c+b|

|a|-|b+a|+|b-c|+|c+b|
= -a - [-(a+b)] + |c -b| + |b-a |
= -a +( a+b) +(c-b) + (a-b)
=c+a -b
=-